Search-light arc-lamp



H. BECK.

SEARCHLIGHT ARC LAMP.

APPLICATION F|LED1uNE15.19l.

.Patented Aug'. 19,

lnvenlfr His Aii/Eorney.

UNITED sTATEs fPATENT oEEIcE.

HEINRICH BECK, OF SCHIEN'ECTADY, N YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A. CORPORATION 0F NEW YORK.

SEARCH-LIGHT .ARC-LAMP.

Application led .Tune 15, 1916.l Serial No.' 103,881.

T0 all whom it may concern.' 1

Be it known that I, HEINRICH BECK, la subject of the German Schenectady, in the county of Schenectady and State of New York, have invented certain new and useful Improvements in Search-Light Arc-Lamps, of which the following is ,a specification.

My invention has reference primarily `to improvements in searchlights, projectors or other like apparatus designed for directing a beam of light outwardly and in which the source of'lightis an arc lamp; but some of the improvements are applicable to arc lamps used for other purposes. The aim of the invention is to render the operation of an arc lamp 'with a large current more secure and uniform, to start the arc and regulate the same automatically by electrical and mechanical devices that may be largely contained within a searchlight casing, and, in addition thereto, to provide means for continuing the control .of the arc in case some of the electrical means provided for 'this purpose, should, for any reason, fail to properly perform the functions assigned to the same.

In the accompanying drawing only the essential part of the mechanism now employed in practice is broadly indicated as follows:-

Figure l is a diagrammatic view of the arc controlling mechanism as a whole and of the circuit connections; Fig. 2 is an' end view, upon. a somewhat larger scale, of the 'anode .head or holder, and Fig. 3 is a vertical 4section of the feed pin coupling.

The anode and cathode are indicated respectively at l and 2, and these electrodes pass through heads or holders 3, 4. The anode is arranged substantially horizontally while lthe cathode is inclined at an angle; with its arcing point directed upwardly. Then the apparatus is not in operation the electrodes are separated as shown, and for starting the arc they have to be first brought into contact and then again Separated. The'.

electrodes are continuously rotated .each about its own axis and are fed toward each other to compensate for their consumption. The rate of the forward feed of the cathode is determined purely mechanically while the rate of the feed ofv the anode is normally controlled electrically by a thermostat, and only when the latter 'failsis the feed of- Emperor, residing at Vwith mechanism which ent-ers into and modifies 'is about 120 volts.

-muth or in a vertical plane.

the anode determined purely mechanically.4 The rotation of the electrodes about their axes is effected by the rotation of their heads or holders 3, 4 by suitable gearing whichis actuated b an ele trie motor and by the rotation o the hes/icds, and in cooperation at the proper times the operation of the heads, the electrodes are fed forward to compensate for consumption. The are is vestablished by another electric motor, which propels the head or holder of the cathode forwardly until the catho-de makes contact with the anode and then withdraws it from the same. There is, thus, one electric motor which controls the rotation vof both elec- Specication of Letters Patel-it. Patented illlg. 19, 1919.

trodes about their axes and influences the feed of the electrodes and thismotor I call the feed motor; and there is another electric motor whose sole function is to establish the arc, andthis motor I call the arc establishing motor. This, in broad outline, is the Inode of operation of my system, and the sequence of these operations and the means by which the sequence is determined I shall now describe in greater detail.

Current is supplied to the apparatus by the mains 5, G, by closing the main switch 5', and these mains are kept at a constant difference of potential by the distant generator. As a rule this difference of potential In the negative main 6 there is a rheostat 7 by, which the current admitted to the arc is regulated; for searchlights the current employed maybe as low as 60 amperes and as high as 300 amperes.- A subsidiary negative main 6 shunts the rheostat and these three mains must beunders-tood to be connected with the `circuits entering the searchlight bysome ieXible or sliding connections which do not interfere with the turning of the searchlight i'nazi- These are appliances I'that are well` understood in the art l and it is therefore' not necessary to illustrate the circuits entering the apparatus with the mains is in the drawing Indicated as fixed. The main branch which enters the apparatus from the mains is indicated by the conductors 8, 9.and these are here shown diagrammaticallyas connected directly to the anode and cath/ode respectively; it will be underpart of the 17 which meshes with the miter wheel 18.A

whose vertical shaft 19 carries two other miter wheels 20, 21, the former meshing with the miter gear 22 and the latter with the much larger miter gear 23, which forms'a head'or holder 3 of the anode; and by this connection the head 3 isrotated in a bearing which is conveniently indicated at 32".` The miter gear l 22 is-at onel end of a countershaft 24 at the other. end of which is ajmiter gear 25 meshing with the miter gear 2 6 on a vertical shaft 27 which, at its upper 1 end, has a miter gear 28 meshing with the much larger miter wheel 23 which is a part of the head or holder 4 of the cathode; and .by this connection the cathode head-is ro- A tated.

The countershaft 24 is-made in two partsV which are connected by a coupling 29, to.

which the left hand part of the countershaft issecured by a pin 30 or in any other suitable fa'shion'. This coupling receives in an axial bore the right hand part of the countershaft so that it can freely slide ftherein, and a pin 31 from this part of the countershaft passes through a slot in the coupling lso that .while this right-hand side of the 'countershaft can freely slide within the bore of. the coupling the pin clutches the latter to,l the countershaft so that it has to turn with the same. The system of gearing here described for rotating the electrode heads 3, 4 may of course be changed in a variety of ways without departingfrom my invention.

The miter gears 25, 26 are journaled in a casting 32 through the main body of which passes the screw threaded portion of the elongated shaft 33 of the armature 34 of the starting motor; and a toe 35 downwardly extending from the casting 32, is located between the two switch levers 36, 37 so that when the casting 32 *is* moved horizontally the toe 35 engages withy one or the other of thesey switch levers for a purpose which will appear farther on. The switch levers 36, 37 are near the upper ends connected by a sprlng 38 and the lower ends of these switch levers are in operative relation to three sprlng contacts 39,40, 41. The spring contaots 39 and 41 are connected by a bridge wire 42 and this bridge wire is connected by a conductor 43 with the positive main 5 and the spring contact 40 is connected with the subsidiary negative main 6 by a conductor 44.

The starting motor hastwo field-magnets.

One of these, 45, has one of its terminals connected with the switch lever 37 by conductor 46 and the other terminal is con' `nected with the back contact 47 of the armature 48 of an electromagnet 49, while the front contact 50 is connected with the switch lever 36 by a conductor v51.- The armature 48 is normally raised into engagement with the back contact 47 by a spring, .as indicated. The armature 48 isv connected with one com- -mutator brush of the armature of the startin motor bya conductor 52. The other lie d magnet 53 of the startin' motor 1s connected with the branch con uctors 54, 55

which are tapped to the negative main 6 and the subsidiary negative mai-n 6 respectively. The conductor'55 is connected t6 the second brush of the armature ofthe starting motor through a hand switch 56 which is normally in a closed position as shown. The winding of the. electromagnet 49 is in rived from the .conductors 54 and 55.

vThe' mechanism and circuit connections so far described coperate in starting the are and 'rotating theheads 3, 4 as follows:

When ther-main circuit is closed by the main switch 5, the rheostat lever is understood to be in a proper position to admit the requisite amount of current to the electrodes,

which at that time are separated as shown in the drawing. The normal distance yapart of the tips of these electrodes is vsupposed to be that which is indicated by the dotted line extension at the anode 1. 'Current' is started through the feeding motor. 1 0, through the conductors 8, 12, and by the system of gears hereinbefore described this motor actuates the heads 3, 4 which are thus rotated each about its own axis. The switch levers 36, 37 are at this stage in contact with the spring contacts 40, 39, respectively, and the circuit thereby` established is as follows: from the positive main 5 to the branch conductor 43, bridge wire 42, spring contact 39, switch lever 37, conductor 46, downwardly through field magnet 45, back contact 47, armature 48, conductor 52 to and through the :armature 34 of the starting motor and by loop for the same reasons. By the rotation of the armature 34, its screw threaded shaft operates to Ipropel the casting 32 and with it, the connected gears 25, 26, 28 and 23 toward the right, it being understood that all switch lever -36 over into 'contact j current through'its lsame direction as before while the current these parts are 'so held together that they all have to'move as one, as for instance by a standard 32a rising from the casting 32 and having a bearing 32b for the head 4, and suitably located lugs 32c as guides ,foigthe shaft 27 and for the rod 'F5'. The coupling 29 between the two'parts of the countershaft 24 freely permits this movement. Eventually the cathode makes'contact with the anode and current now flows by the conductors 8, 9 between the contacting electrodes. By this time the toe 35 of the casting 32 has not only moved toward the right to free the switch lever 36 to the action of the spring 38 whereby contact between this switch lever and the spring contact v40 is broken, butthe toe is now far enough to the right to allow the spring 38 with spring contact 41, 'but the toe is not'suii'ciently far to the right to bear upon lswitch lever 37 so as to break contact between the latter and spring-contact 39. At the same time the winding of electromagnet 49 is placed in a live circuitfshunting the resistance 'of the rheostat 7 by lconductors 54, -55 and taking current corresponding to that resistance, since now the negative main 6 carries the return current from the electrodes. The armature 48 of thiselectromagnet is 'therefore attracted and bears upon the front contact 50. This establishes a new circuit for the starting motor as follows: from the positive main 5 by branch conductor 43, bridge wire 42, spring contact 41, switch lever 36, conductor 51, front contact-50 armature 48, conductor 52, to and through the armature 34 of the starting motor and by closed switch 56 at the point 57l to the branch conductor 55, and to the subsidiary negative main 6.

The iield winding 53 now' receives current by the branch conductors 54 and v55, shunting the resistance of the rheostat 7, just as described with reference to magnet 49. The starting motor, therefore, now operates as a shunt motor and it will lbe observed that the armature passes in the through the 'field 53-passes in a direction opposite to that which has been traced through the field magnet coil 45; the motor is therefore reversed and the casting 32 with its connected gearing and with the head 4 are now moved toward the left hand side, thereby starting the arc, and this reverse movement continues until the toe 35v encounters the switch lever 36 which breaks Contact with spring contact 41 and establishes contact with spring Contact 40. By this timethe arc has attained about l'its normal length and while the live circuitI ofthe starting motor as a series motor is now interrupted at back contact 447, and asa shunt motor at spring contact 41, ithas attained a cgnsiderable speed, which, 1f allowed to continue would to carry thel spring contact 41, continue separate the electrodes beyond the normal length of the arc. But the rotation of the motor armature is checked'by the 'fact that it is now on a short circuit, closed upon itself by that part of the auxiliary negative main which extends between the junctions with the same of the branch conductors 44 and 55. The motor thus becomes a generator and acts as anelectromagnetic brake upon itself.

From the foregoing it will be seen that as the casting 32 with itsv toe 35 and the other parts connected therewith is by the starting motor, acting as a series motor, propelled toward the right, the switch leverl 36 is freed to make contact with the spring contact 41 at the moment when Contact between the electrodes is established. At that moment three things occur. simultaneously, namely, current starts in the branch 8 9 so that the return current passes through the negative main 6 and consequently the magnet 49 is energized, drawing down its armature 48, which makes contact with Contact Y50 and thereby converts the starting motor from a series motor into a shunt motor which now operates towithdraw the cathode from the anode, thus establishing the arc, and this arc establishing movement is only interrupted when thetoe 35 has caused a break between the switch lever 36 and spring contact 4l, whereby, as has been shown, the live circuit of the shunt motor interrupted and the motor is put on sl'io'rt` circuit and actsas a brake upon itself. It will vbe seen from this that the length of the arc as established by the starting motor when acting as a shunt motor depends upon the position of the toe 35 of the casting 32 with respect to the upper end 'of the switch lever 36. This necessary relative position, therefore, must be ascertained and established; it is generally different with 'different sizes 'of searchlights. It will also be seen that up to the point of operation so far described there is no reason why the switch lever 37 should be movable, since, so far as described, it does not break contactl with the spring Contact 39; it would, therefore, seem that the contact between these two elements might be xed. But it sometimes happens that a piece or the whole of either or both electrodes breaks ofi', or that the electrodes have not initially been adjusted close enough, or that by some'\mistake no electrodes have been inserted in place before the operatioirof the arc establishing mechanism is started. Whenany of these things happens the starting` motor` as a series motor, would, even after, switch lever 36 has broken contact with the spring contact 40 and made contact with to move the cathode toward the right and jam the electrode heads together and cause injury to either or both heads. In order to guard against this contingency,

is moved toward the right beyond the position where it allows the switch lever 36 to part contact with contact with l,the element 41, the toe 35 will engage the lever 37 and break its contact with spring contact 39, whereby the starting motor is open circuited and the advance of the cathode toward the anode. is stopped before any injury can be done. The switch lever 37, therefore, is a safety switch lever. The two heads or electrode holders 3, 4 are constructed substantially 'alike, but the details that are shown in connection with head 3, but the end views shown in Fig. 2 is a correct illustration of both heads. Therefore, referring now particularly to the upper right hand side of Fig. 1 and to Fig. 2, it will be seen that a worm 58 is journaled eccentrically in the miter wheel 23 by a shaft 59 which also carries a spur wheel 60, and on the same shaft is a pinion 61 which meshes with the internal gear 62. This internal gear 62 is parallel to and concentric with the miter wheel 23 but is journaled independently thereof. To the frame,

A63 of the head 3, are pivoted two arms 64, 65, in thefree ends of which are journaled two gears 66, 67 whichmesh with each other. The shaft of gear wheel 66 also carries at its other end a gear 68 whichl meshes with the worm 58; and between' the gears 66 and 68l $5 the same shaft carries a flanged pulley 69 which receives upon its flanges the elec trode 1. The shaft of v he gear 67 carries a lmurled wheel 70, bearing upon the electrode, and a spring 71, connecting the two arms 64, 65, keeps the ears 66 and 67 in engagement with each ot erand the flanged pulley 69 and knurled wheel 7 0 in engagement with the carbon which passes betweenthem; the same springl also holds the gear 68 in engagement with the worm 58. v

IThe operation of the heads, 3, 4 of rotating the electrodes about their axes and feeding the same is as follows: The carbon 1 passes ythrough the .bushing 72 and between the flanged pulley 69 and knurled wheel 70. When the. feeding motor lactuates the miter wheel 23 the whole head 3 is rotated and the electrode being held between the pulley 69 and knurled wheel 7 0 is rotated with the head. rDhe electrode 2 is rotated in the same manner with the head 4, by the' miter wheel 23', and need not' be further described.

In this `operation the spur wheel 60 and the pinion 61 both of which are eccentrically .mounted in the head are revolved about the axis of 4the electrode and thus describe a circular orbit as a part gearing.` The pinion 61 acting as a clutch upon the internal gear 62 Acauses the latter' 05 to rotate about'its own axiswhich is coincithe element 37 is made as alever, so that when the casting 32 the element 40 and make ,about its own axis,

lare secured. This worm head 4 is in Fig. 1 not shown with all the" freely pass' the spur;

i 73', while the core of the planetary y l axis of the electrode; but neither the spur wheel nor the pinion 61 rotates about its own axis; nor does the worm 58, nor the gear wheel 68, nor the gears 66, 67 and flange pulley 69 and knurled wheel 70 rotate about their axes. In other words the electrode is simply rotated about its axis but is not fed forward.

dent Awith the i But if now by some means, which will presently be described, the spur wheel 60 receives a tangential thrust, it will be rotated that is to say, with its shaft 59 to which'pinion'61 and the worm 58 therefore will now rotate about its axis and actuate thegear wheel 68 and the latter by the shafting and gearing connected therewith will cause the flanged pulley 69 and knurled wheel 7 0 to rotate each about its axis and thereby propel the electrode forwardly. The tangential thrust upon the spur wheel 60 required for this operation is brought about with respect t0 head 3- as follows: v

little lever 73 mounted on a There is a stationary part of the apparatus and right hand side of this lever has a spur I so located that when the lever is in the position shown in the drawing a pin 74 projecting laterally from the binternal gear 62w1l1 ut side of the lever 73 is raised 'above the position shown on the drawing the pin 74 will, when the internal gear rotates, strike the spur 73 and thus arrest l To the left hand arm of the lever 73A is pivoted a pin 7 5, a finger extension 76 of which rises some hat' above the lever. The lower end of the pin 75 bears upon the left the if the right hand the internal gear.

hand arm of asmalllever 77 which in turn' 75 upon the left hand arm 0f lever 77 ,and

desired position by a handle 79 from the latter u pon the cam or eccentric 7 8,

while the right hand arm of lever 77 1s therebyvraised against an adjustable nut 82 on a stem 83 extending from the core of an electro-magnet or solenoid 84. By this arrangement the finger 76 can be adjusted to a higher or lower position by turning the eccentric 78 to the left or'to the right, respectively, and to these adjustments corre spond a lower or higher position 'of the spur ofthe solenoid is thereby always held in an elevated or unattracted position. The coil of solenoid 84 is in a branch 85, 86, derived from the are conductors 8, 9; this branch includes a hand switch 87 and a thermostat 88 composed of the thermostatic strip or strips 89 and contact'QO .An optical system composed of a coniao the heat upon the thermostaticstrips. The

and the thermostatic meter) of the anode densing lens 91 and a mirror 92 is arranged with reference to the crater of the anode strip in such manner portion (about 1 millihas been consumed, the heat rays from the same strike the thermostatic Strip, as indicated by the dotted lines 93, 94, whereupon this strip buckles rearwardly as indicated by a dotted line and thereby closes the solenoid circuit; the core of the solenoid is drawn down, the left hand arm of the lever 77 is raised above the eccentric 78 and thereby raises the pin 75 with its finger 76 and depresses .the right hand arm of lever 73 still farther out of the path of the pin 74 projecting from the internal gear. In the drawing the solid lines show the condition where the anode has been consumed sufficiently to haveI its heat rays just thrown upon the thermostatic strip, but it Ais assumed that the latter has not yet been heated sutiiciently to close the solenoid circuit and therefore the core of the solenoid is not shown'in its attracted position, and consequently the pin 75 has not yet been raised above the eccentric. lThe operation of feeding the anode can now be described.

Normally the eccentric 78 is adjusted so that the left hand arm of lever 77 bears upon a somewhatl elevated position of the eccentric. This slightly'raises the finger 76 but not sufficiently to` get into the way of the spur wheel as it describes its circular orbit hereinbefore explained. This is the position of the parts shown in the drawing. When the anode has been consumed to the extent indicated in the drawing so that the heat rays from the crater become concentrated upon the therlnostatic strip or strips, the latter, after av second o r two, buckle rearwardly and close the branch circuit 85, 86, and thereby the solenoid is energized, the core of the latter is drawn down against the action of the spring S1 and the pin 7.5

that when a certain is raised sutHciently to bring'its finger 76 into the path of the sp-ur wheel 60. This spur wheel now receives at each revolution of the head' 3a tangential thrust by the linger 76 -which enters deeply between its teeth. The Aspur wheel therefore is now forced to rotate about its own axis, thereby rotates the worm 58 and by the gearing connected therewith the anged pulley 69 and knurled wheel 70. The anode is there fore lpropelled forwardly, and it -is propelledmuch faster than is required to compensate for its consumption, until its crater fails to send its heat rays upon the optical system in' such direction as to concentrate i f` lattercool rapidly and straighten out to the A vposition shown in solid lines, wherebv the "branchvhf85, 86, is opened'.

the solenoid deenergizd and the'pin 75`wi'tl1 its finger 76 'heat rays from 'it slightly counter-clockwise,

and this is accomplished by is drawn down by the spring 81 to the position shown in the'drawing while the core of the solenoid is raised also to the position shown in the drawing. This rapid feeding operation is repeated as often as the'anode far described, is the preferable 011e, it is evident that the mechanism shown lends itself to a slightly different mode of operation which I have -also practised successfully. This modified mode of operation is secured by adjusting the cam 78, by turning so that it will raise the left-hand end of lever 77, above the position shown in the drawing and thereby will also raise the pin 75, with itsnger end 76, above the position shown vlin the drawing and sufficiently high to normally lbe in the way of the spur wheel as it describes its circular orbit and projects slightly between the spurs thereof. With this adjustment it will be seen that at each revolution of the planetary gear there will be impact between ythe spur wheel and ithe finger 76, so that the electrode will be propelled periodically forwardly in partial compensation for the consumption which has occurred. In all other respects the operation will be as hereinbefore described, so that when, notwithstanding the slight periodic feed of the anode at eachw'revolution the consumption accumulates sufficiently to require the restoration of the crater mouth to its focal position, the thermostatic system will come into action. These are the normal operations of the feeding of the anode; but if by some accident any considerable forward portion of the l anode should break off whereby the arc is broken, a much faster forward feed of the anode is required, in order to restablish the arc;

A j the manipulation of the eccentric by the attendant. He turns this eccentric clockwise and thereby brings its lowest point under the lever 77. The pin 75 is thereby lowered to a correspondingly low position by the spring 81, whereby the right hand arm of the lever 73 is raised sufficiently to bring the spur 73 into the path of thepin 74 projecting from the internal gear. This internal gear is thereby arrested and the pinion 61 which` engages it and which continues to describe its circular orbit is rapidly rotatedA about its axis and rapidly rotates the worm` 58. The anode is thereby propelled forwardly with great speed so as to coperate with the cathode to restablish the arc in the manner hereinbefore described. As soon as the'arc has again attained its normal length and the attendant turns the eccentric counter-clockwise to bring a more elevated point of it under the lever 77 (such, for instance as shown in the drawing) normal feeding operation is periodically resumed. f

If by some accident the thermostat should fail to operate, or if for any reason the pin 75 should fail to be raised by the solenoid kso as to bring the finger 7 6 between the teeth of the spur wheel 60 when the normal periodic feed of the anode is required, a periodic feed may be secured by the attendant by turning the eccentric 7 8 counterclockwise so as to bring a higher point plf t e finger 76 is raised to-a periodically enters between the teeth of the spur wheel 60 sufficiently to cause periodic feeding of the anode. This purely mechanical controll of periodic feed must be regulated by the attendant to be sufficientto compensate for the consumption of theanode and he can regulate it by turning the eccentric accordingly. This purely mechanical control of feeding of the anode requires intelligent observation ofthe attendant and vthis practice is only Aresorted to in case of a break-down of the thermostatic control; but it is a very important accessory thereto.

The feeding of the cathode is controlled purely mechanically in substantially the same manner as the the periodic' feed of the anode when the thermostatic control fails. The pin 75 is by the attendantraised to a. sufficient height, by the setting of the eccentric 78, to bring the upper end into the path of the spur wheel, once during each revolution of the head 4, the spring 81 always holding the pin 75 in contact with the surface of the eccentric. The rate of feed of the cathode is primarily determined by the ascertained consumption of this electrode under normal conditions; but this rate of consumption may vary according to the more or less perfect uniformity of this` electrode from point to point and if any considerable deviation from the normal rate of consumption develops, the eccentric 78 has to be set to a different point. But it has been found in practice that the variations of consumption o-f the cathode are insignificant or at any rate of no great importance, since it could only affect the length of the arc; but in searchlights of this character no dependence is placed upon the luminosity of the arc, the real source of light being the crater of the anode. It is therefore the position of the anode in the focus of the reflector which is used in such apparatus that is of importance.

In the operation of feeding the electrodes by the coperationof the feed pin 75 and the spur wheel 60, it may happen, and it actually frequently happens that the pin as shown, whi

strikes the point of a spur instead of entering between two adjacent spurs. When this happens, the feed pin, if lmade a rigid structure, may stop the rotation not only of the spur wheel 'but of the whole head (3 or 4:) and thus the feeding operation with and injury may be done to the mechanism. In order to avoid such accidents and assure regular feeding operation I make the feed pin in two parts, 7 5a and 7 5b, joined by a coupling 7 5", as shown in Fig. 3. The

is interferedl coupling 7 59 is a sleeve into the lower end yf which the lower part '75h ofthe feed pin is adjustably sec red, as by a screw and nut, the upper part 75a of the feed pin loosely passes into the upper part of the sleeve and is guided therein, as shown, by a bushing 75c1 and by the bore of the lower part of the sleeve. A pin 75e passes transversely through the part 7 5il and through a transverse slot 7 5f in the sleeve, and a coiled spring 7 5g holds the part 75l elevated with the pm 7 5e at the upper end of the slot 75.

With the special construction of the feed pin here described the feeding operation takes place without hitch, because, when it happens that the feed pin strikes the point of a spur of the spur wheel 60, the upper part 759L spur wheel clears the point of the pin,

-at thev next instant when the pin is thrust back to its elevated 'position by the spring 7 5g, the pin may freely enter between two adjacent spurs of the spur wheel.

v Inorder to reduce the consumption of the electrodes, to secure the formation of a deep, well formed crater in the anode and for other reasons which it is not necessary here to dwell upon, I use in my. searchlight apparatus means for immersing the arcing points of the electrodes and portions behind yields to the impact so'that thev the arcing points in a non-oxidizing and l `become ignited and envelop the ends of the electrodes by a flame; but this fiame is so very much cooler than the ends of the electrodes that it acts as a cooling agent upon the-same'. Since this feature is not a part of my present invention it is not necessary to describe it in more detail and a reference to the patent aforesaid is deemed to be sufficient. i

The details of the mechanism and circuit connections I have herein only broadly indicated and the same can be varied in many ways without departing from my invention. Likewise I have not attempted to will know that in the construction of the feeding pins (75 and 75) the spring 75g must be much stiffer than either of the springs 8l or 81. Numerous other features of this kind might be pointed out. Also, it will be understood that the optical system for directing the radiant energy from the crater of the anode upon the thermostat may be variously changed and that in place of a thermostat sponsive to radiant energy, such, for instance as a selenium cell, may be used.

VVihat I claim 'as new and desire to secure by Letters Patent of the United States, is:-

An arc lamp, comprising a pair of electrodes and controlling and regulating means for the same, constant potential -mains connected with the electrodes, a rheostat in one of the mains for controlling the arc current and branches from thel mains for diverting to some of the means the potential difference between the mains in advance of or 'behind the rheostat, respectively, an'd to others the potential difference across the rheostat. 2. In an arc'lamp, a pair of electrodes, constant potential mains connected with the same, a rheostat in one of the-mains for controlling the Iarc current, a motor receiving the full constant potential, gearing actuated by the motor for rotating both electrodes, each about its axis, and for feeding the anode to compensate for consmnption, an arcl establishing motor for propelling thev cathode into contact with the anode, and means for reversing the motor energized by the difference of potential across the rheostat.

3. In an arc lamp, a pair of electrodes, constant potential mains connected with the same, a rlieostat in one ofl the mains for controlling the arc current, an arc establishing 'motor receiving the full constant potential for propelling the cathode into contact with the anode, and means for reversing the motor energized by the difference vof potential across the rheostat when current rstarts between the electrodes.

4. In anarc lamp, a pair of electrodes, constant potential mains connected with the same` a rheostat in one of the mains, an are establishing motor for propelling the cathode toward the anode, means for reversing the motor energized by the difference of potential across the rheostat when current starts between the electrodes, and means controlled by a part moving with the cathode forl breaking the active motor armature circuit and short circuiting it when the arc has attained the desired length. y In an arc lamp, a pair' -of electrodes tion o'f the electrodes the cathode is pelled l forwardly beyond the normal disother devices that are renet circuit when the between adjacent normally 'separated aV definite distance when there is no current on the lamp, an arc establishing motor for propelling the cathode forwardly into contact with the anode, and means controlled by a, part moving with the cathode for breaking the motor circuit when by reason of anabnormally large separaprotance.

6. `In an arc lamp, a pair of electrodes, 'mechanism for feeding the anode stepwise toward the cathode to more than compensate for'the consumption of the former ateach step, a normally open-circuited electro-magnet for actuating when energized the feeding mechanism, and automatic means for closing the circuit of the electro-magnet when the an-ode consumption has reached a pre-determined poin-t.

In an arc lam-p, a pair of electrodes, means for feeding the anode stepwise toward the cathode to more than compensate for the consumption of the former at each step, a

normally open-circuited electro-magnet for actuating when energized the feeding means, a thermostat for controlling the circuit of the electro-magnet, and an optical system for directing the radiant heat from the anode crater upon the thermostat to Iclose the maganode consumption has reached a predetermined point.

' 8. In an arc lamp, a pair of electrodes, a rotatable head'y or holder for each electrode, a motor for rotating each holder about the axis of the corresponding electrode, a planetary gear carried by each holder and geared to the holder for feeding the electrodes to compensate for consumption, and means eX- ternal to the holders adjustably arranged to intermittently react upon each planetary gear to actuate the same to the desired eX- tent.

an electrode and Iholder for the same, means for rotating the holder and electrode about their common axis; a planetary gear carried by the holder and geared with the latter trode to compensate for consumption, means external t0 the holder adapted to project at one point into the orbit of the planetary gear to actuate the latter once during each revolution, and means forl adjusting the depth of projection and thereby the extent of electrode feed. u

10. In an arc lamp, an electrode and holder for the same. means for rotating the holder and electrode about their common axis, a spur wheel and worm on a shaft carriedby the holder eccentric to the'aXis of the latter, the worm engaging a system of gears for feeding the electrode to compensate for consumption, a pin adapted to be projected spurs of the spur wheel,

9. In an arc lamp,

for feeding the elecv holder for the same,

` two parts connected by a toward and from and a cam for adjusting the depth of pro"- .jection. j y j 11. In an are lamp, an electrode and holder 'for the same, means for rotating the holder and electrode about `their common axis, an internal gear wheelindependently rotatable about the same axis, a -pinion and a worm on a shaftmounted eecentrically in the holder, said pinion being in clutching engagement with the internal gear and thereby rotating the latter and the worm engaging a system of gears for feeding the electrode to com-l pensate for consumption, and means external to the holder for stopping the internal gear wheel and thereby rotating the pinion and worm shaft to feed the electrode at high speed.

12. In an' arc lamp, an electrode and holder for the same, means for rotating the holder and electrode about their common axis, a pinion, a spur wheel and a worm on a shaft mounted eccentrically inthe holder, an internal gear independently rotatable about the common axis of holder and electrode, a system of gears in engagement with r tliey worm for feeding the electrode, Said pinion being normally in clutching engagement with the internal gear so as to rotate thesame, a pin external to the holder adapted to be projected toward the latter between adjacent spurs of the spur wheel, means adapted to be moved by said pin the internal gear wheel to stop or release the same ywhen the pin is withdrawnl from or projected into the spur wheel, respectively, and means forrmoving said pin to either position.

13. In an arc lamp, 'an electrode and holder for the same, means for rotating the holder and electrode about their common axis, means for feeding the electrode, electro-niagnetic means for actuating the feed ing mechanism when -tlie electrode consumptionl has reached a predetermined point, and hand controlled alternative means 'for periodically actuating the feeding mechanism. J A

14. oIn an arc lamp, an electrode 'and means for rotating the holder and electrode' about their common axis, a spur wheel and worm on a shaft carried by the holder eccentric to the axis of the same, the worm engaging a system vof gears for feeding the electrode to cornpensate for consumption, a pin made in spring and means the pin toward the spur for proj ectinglA same whereby when wheel for actuating the 1 l Vthe pin strikes a spur of the wheel it will rebound and then enter between adjacent spurs andtuin the wheel about its axis..

l5. In an arc lamp, a pair of electrodes for rotating the anode yabout its axis, gearing for rotating the cathode about its axis, a motor for actuating both gearings, a motor for moving the cathodewith its holder and an arc starting motor, circuit connections from the mains and the auxiliary main to the arc starting motor, a system of switches controlled by the motor anda switch controlled by an electro-magnet shunting the rheostat, these switches coperating to cause the motor to rotate to move the cathode into contact with the anode and then reversing the motor and withdrawing the cathode.

17. In a searchlight, the combination with an electrode, of a holder therefor, a rotatable member on said holder for rotating the electrode, means for continuously rotating said I nemb'en-a feeding device for said electrode incuding a stop and a member adapted to be moved thereby on rotation of said rotatable member, and means whereby the po-v sition of said stop maybe the feed.

18. In a searchlight, the combination with an electrode and means for 'rotating the same about its axis, a device for feeding varied to alter the electrode actuated at periods controlled I by the speed of rotation of the electrode,

and means for adjusting the rate of feed per period.

v19. In a searchlight, the combination with an electrode, of a holder therefor, a rotatable member ofv said, holder for rotating the electrode about its axis, means .for continuously rotating said member, a periodically actuating feeding device for said electrode, and means for adjusting the rate of feed per period.

20. In a searchlight, the combination with an electrode, of a holder therefor, )a rotatable member on said holder for rotating the electrode about its own axis, a feeding device for said electrode carried by said member, and means for periodically actuating the feeding device and lfor adjusting the rate of feed.

21T An electrode holder for searchlights 22. In a searchlight, the combination with actuated by the said movement of said dean electrode, of a holder therefor', a rotatable vice for feeding the electrode through the member on said holder for'rotatng the elec-l holder, and means whereby the position of 10 trode, means for continuously rotating said said stop may be varied to alter the feed.

5 member, a stop, a device connected to Said It Witness whereof. I'have hereunto set member for revolution therewith and adapt-v my hand this 14th day of June, 1916. ed to be moved by striking said stop, means HEINRICHBECK. 

